The recent advent of M2M (Machine-to-Machine) available and high data processing devices including smart phones or tablet PCs has led to an increase in data transmission over a wireless communication network. To satisfy increasing data transmission, more attention is being directed toward cognitive radio (CR) and carrier aggregation (CA) for efficient use of more frequency bands and multi base station collaborative and multi antenna technologies for increasing data capability within a limited frequency resource.
The wireless communication network is evolving to have a higher density of nodes accessible by a user. The “node”, which is sometimes referred to as an antenna or antenna group spaced apart from a distributed antenna system (DAS), may have a broader meaning. For example, the node may be one of a macro base station, pico cell base station (PeNB), home base station (HeNB), RRH (Remote Radio Head), RRU (Remote Radio Unit), relay, or distributed antenna (group).
With a higher density of nodes, a wireless communication system may exhibit higher system capability through collaboration between the nodes. For example, even more excellent system capacity can be achieved when each node operates as an antenna or antenna group for one cell while its transmission/reception is managed by one control station rather than when each node operates without cooperation with another with respect to a base station. Hereinafter, a wireless communication system including multiple nodes is referred to as a “multi-node system.”
In a multi-node system, a base station may assign a node set to a terminal in a semi-static or static manner. The base station may dynamically select the nodes included in a subset of the node set and may transmit a signal to the selected nodes. In such case, to select the optimum nodes, the base station theoretically requires channel state information for all the subsets included in the node set. If the terminal feeds back the channel state information for all the sub sets to achieve such purpose, the calculation of the terminal may be more complicated together with more consumption of resources for feedback information.
There is a need of a channel state information feedback device and method that can optimize capability of a multi-node system.